The consumer products industry has long searched for ways to enhance the performance of fabric care products, like a fabric softener, and to make the products more esthetically pleasing to consumers. For example, fragrance is an important ingredient in successful commercial fabric care products because, in addition to imparting an esthetically pleasing odor, a fragrance conveys a positive image of product performance to the consumer, e.g., the fabric is clean and fresh.
Fragrances typically are added to fabric care products to provide a fresh, clean impression for the product itself, as well as to the fabric treated with the product. Although the fragrance does not enhance the performance of a fabric care product, the fragrance makes these products more esthetically pleasing, and consumers expect and demand a pleasing odor for such products.
A fragrance plays an important, and often a determining, role when the consumer selects and purchases a fabric care product. Many consumers desire the fragrance to be deposited on the fabric and remain on the fabric for an extended time in order to convey a continuing impression of freshness. Consumers also desire fabric care products that impart a sufficient fragrance level to the fabric, and, in some embodiments, release the fragrance when the fabric is ironed.
Introduction of a fragrance into a fabric care product is restricted by considerations such as availability and cost, and also by an inability of the fragrance to sufficiently deposit onto a fabric, and then remain on the fabric during the wash, rinse, and drying cycles. For example, a substantial amount of the fragrance deposited on a fabric is removed from the fabric during the drying process, even when the treated fabrics are line dried. It also has been demonstrated that a substantial amount of the fragrance in currently available fabric care products is lost during rinse cycles. This fragrance loss is attributed to the water solubility of various fragrance ingredients, and to the volatility of fragrance ingredients that deposit on the fabric.
Typical fabric care products, such as laundry detergent compositions and fabric softener compositions, contain about 0.1% to about 1%, by weight, of a fragrance. U.S. Pat. No. 6,051,540 discloses that in the course of the washing clothes with a standard powdered laundry detergent, or a fabric softener rinse, only a small fraction of the fragrance present in these fabric care products is actually transferred to the fabric, i.e., as low as 1% of the original amount of fragrance present in these products.
Attempts have been made to increase fragrance deposition onto fabric, and to hinder or delay the release of the fragrance from the fabric, such that the laundered fabric remains esthetically pleasing for an extended length of time. One approach uses a carrier to introduce the fragrance to the fabric. The carrier is formulated to contain a fragrance and to adhere to the fabric during a washing cycle through particle entrainment or chemical change.
Fragrances have been adsorbed onto various materials, such as silica and clay, for delivery of the fragrance from detergents and fabric softeners to fabrics. U.S. Pat. No. 4,954,285 discloses fragrance particles especially for use with dryer-released fabric softening/antistatic agents. The fragrance particles are formed by adsorbing the fragrance onto silica particles having a diameter of greater than about one micron. The fragrance particles are included in dryer-activated solid fabric softener compositions including coated particles of fabric softener. The compositions release softener to fabrics in the dryer, and the fragrance particles improve the esthetic character of the fabric softener deposited on the fabric. The fragrance particles also can be admixed with detergent granules and can be coated or uncoated. This system has a drawback in that the fragrance is not sufficiently protected, and frequently is lost or destabilized during processing.
Another problem often associated with perfumed fabric care products is excessive odor intensity. A need therefore exists for a fragrance delivery system that provides satisfactory fragrance both during use and from the dry laundered fabric, and also provides prolonged storage benefits and an acceptable odor intensity of the fabric care product.
U.S. Pat. No. 6,790,814 discloses that a fragrance loaded into a porous carrier, such as zeolite particles, can be effectively protected from premature release of the fragrance by coating the loaded carrier particles with a hydrophobic oil, then encapsulating the resulting carrier particles with a water-soluble or water-dispersible, but oil-insoluble, material, such as a starch or modified starch.
U.S. Pat. Nos. 4,946,624; 5,112,688; and 5,126,061 disclose microcapsules prepared by a coacervation process. The microcapsules have a complex structure, with a large central core of encapsulated material, preferably a fragrance, and walls that contain small wall inclusion particles of either the core material or another material that can be activated to disrupt the wall. The microcapsules are incorporated into a fabric softener composition having a pH of about 7 or less and which further contains a cationic fabric softener. The encapsulated fragrance preferably is free of large amounts of water-soluble ingredients. The microparticles are added separately to the fabric softener compositions. Ingredients that have high and low volatilities, compared to desired fragrance, either can be added to or removed from the fragrance to achieve the desired volatility. This type of controlled release system cannot be used with all types of fragrance ingredients, in particular, with fragrance ingredients that are relatively water soluble and/or are incapable of depositing onto a fabric.
U.S. Pat. No. 4,402,856 discloses a coacervation technique to provide fragrance particles for fabric care products containing gelatin or a mixture of gelatin with gum arabic, carboxymethylcellulose, and/or anionic polymers. The gelatin is hardened with a natural and/or synthetic tanning agent and a carbonyl compound. The particles adhere to the fabric during rinse cycles, and are carried over to the dryer. Diffusion of the fragrance from the capsules occurs only in the heat-elevated conditions of a dryer.
U.S. Pat. No. 4,152,272 discloses incorporating a fragrance into wax particles to protect the fragrance during storage and through the laundry process. The fragrance/wax particles are incorporated into an aqueous fabric conditioner composition. The fragrance diffuses from the particles onto the fabric in the heat-elevated conditions of the dryer.
U.S. Pat. Nos. 4,446,032 and 4,464,271 disclose liquid or solid fabric softener compositions comprising microencapsulated fragrance suspensions. The compositions contain sustained release fragrances prepared by combining nonconfined fragrance oils with encapsulated or physically entrapped fragrance oils. These combinations are designed such that the nonconfined fragrance oil is bound in a network of physically entrapped fragrance oil and suspending agent. The controlled release system comprises a mixture of (i) a nonconfined fragrance composition, (ii) one or more fragrance oils which are physically entrapped in one or more types of solid particles, and (iii) a suspending agent such as hydroxypropyl cellulose, silica, xanthan gum, ethyl cellulose, or combinations thereof. The nonconfined fragrance, the entrapped fragrance, and the suspending agent are premixed prior to preparation of the liquid or solid fabric softener compositions.
U.S. Pat. Nos. 4,973,422 and 5,137,646 disclose fragrance particles for use in cleaning and conditioning compositions. The particles comprise a fragrance dispersed within a wax material. The particles further can be coated with a material that renders the particles more substantive to the surface being treated, for example, a fabric in a laundry process. Such materials help deliver the particles to the fabric and maximize fragrance release directly on the fabric. In general, the coating materials are water-insoluble cationic materials.
U.S. Pat. No. 6,024,943 discloses particles containing absorbed liquids and methods of making the particles. A fragrance is absorbed within organic polymer particles, which further have a polymer at their exterior. The external polymer has free hydroxyl groups, which promote deposition of the particles from a wash or rinse liquor. The external polymer can be a component of an encapsulating shell, but typically is used as a stabilizer during polymerization of the particles. A highly hydrolyzed polyvinyl alcohol is a preferred external polymer.
U.S. Pat. No. 6,740,631 discloses a free-flowing powder formed from solid hydrophobic, positively-charged nanospheres containing an active ingredient, such as a fragrance, encapsulated in a moisture sensitive microsphere. To maximize deposition of the nanospheres on a fabric, particle size is optimized to ensure entrainment of the particles within the fabric fibers, and a sufficiently high cationic charge density on the particle surface is provided to maximize an ionic interaction between the particles and the fabric.
U.S. Pat. Application No. 2003/0166490 discloses solid spheres comprising a crystallized waxy material. The waxy material may have a fragrance or other active agent incorporated therein, together with a cationic, hydrophobic charge-enhancing agent and a cationic softening agent. The spheres adhere to a fabric because of the cationic charge, and when ironing a dried fabric, a burst of fragrance occurs. The load of fragrance or other active agent is limited to about 30%, by weight, of the waxy material.
U.S. Pat. Application No. 2006/0014655 discloses the delivery of a benefit agent that is introduced into a formulation after admixture with a carrier. The agent and carrier composition requires a viscosity of at least 400 cps.
Delivery systems often are used in personal care and pharmaceutical topical formulations to extend release of the active ingredient, to protect the active ingredient from decomposition in the formulation, and/or to enable formulation of the active ingredient into the compositions due to difficulties, such as solubility or formulation esthetics. However, a need remains in the art for an efficient, controlled delivery system to effectively deposit active ingredients, such as fragrances, onto a fabric. One type of delivery system that can achieve these attributes in a formulated product is the adsorbent microparticle delivery systems.